1. Field of the Invention
The present invention relates generally to the field of watercraft hull configuration, and more particularly to an engine-powered watercraft having three parallel hulls, with the center of the three hulls being of a v-form having varying deadrise depending on the purpose of the craft and two or more transverse steps, and two outer hulls, i.e., amas, having considerably greater reverse deadrise facing the deadrise of the center hull and vertical outboard surfaces.
2. Description of the Background Art
Entrapment tunnels of the prior art typically either keep the entire tunnel completely wet or completely dry. There are drawbacks to both methods. For example, completely wetted tunnels experience increased drag. On the other hand, completely dry tunnels cause watercraft instability. It would be desirable to reduce viscous drag of a watercraft and contemporaneously improve the stability using a combination of allowing the tunnel to be both wet and dry, thereby overcoming such drawbacks.
In watercrafts with conventional stepped hulls, the steps can be ventilated using step cut-outs. The suction created by water separating and reattaching on the hull immediately aft of the step in the step cavity draws air in from the ambient surroundings via the step cut-outs. For this reason, it is normally desirable to leave the outboard openings of the step cut-outs without obstruction, that is, to ensure that ambient air is always free to flow into the step cavity. Also for this reason, stepped hulls are not typically used in combination with tunnels, channels, etc., since it is thought that these structures would interfere with the ventilation of the step cavities. It would be desirable for amas to be used in conjunction with stepped hulls. Amas improve static and dynamic stability, add planing lift, improve directionality, and provide a structural stand-off from the main hull, fendering the main hull from impacts at the waterline.
In prior art, if stepped hulls are used with amas, they are made in conjunction with adequately large air entrapment tunnels so that the flow of atmospheric air is not constricted from entering the step cavities. It would be desirable to remove the necessity of having large air entrapment tunnels when amas are used with stepped hulls, both to meet size constraints, as well as to reduce the drag and weight of a larger structure.
In view of the foregoing, it would be desirable to provide system, apparatus and methods to reduce drag and to improve stability for stepped planing watercrafts.